The present invention relates generally to a simplified machine control device, and more particularly to a device that reduces the complexity of the user interface for controlling blade position in earth-grading machinery.
In construction and related earth-moving job sites, an on-site elevation positioning or guidance system can be used in conjunction with earth-grading machinery, such as bulldozers and earthmovers, to provide information about, or control blade lift (also known as grade or elevation) and tilt (also known as slope or side-to-side angle) of, the blade relative to the ground being graded in order to cut and fill earth in accordance with a predetermined grading plan. In “indicate-only” systems, guidance information is provided, whereas in automated systems, the information derived from the differences between the current and desired blade positions can additionally be used to drive the blade to a preferred position. Detectors mounted at locations (typically two) across the blade sense a remotely-generated signal from the system's transmitter, which may generate a horizontally-swept beam (such as a laser) to provide a reference plane. The sensed signals are compared against a predetermined reference to determine if the blade needs to be raised or lowered. Differences between the sensed signals and the reference are used to control the movement of hydraulic valves (or related actuators) coupled to the blade, where the valves are responsive to either user input commands (in manual operation) or to control signals (in automatic operation). An elevation positioning or guidance system that employs equipment for display and control of blade lift and tilt is known as a dual elevation machine control system.
In an independent mode of dual elevation blade control, each side of the blade (or, as typically the case in a bulldozer, one side and the center of the blade) can be autonomously moved, through either of the aforementioned manual or automatic methods. Positions associated with each side are displayed on a screen for viewing by the operator. While the independent mode of control of a single blade (or the control of two blades in the case of a tandem-blade device) of the dual elevation machine control system gives the operator significant flexibility, such as enhanced levels of blade adjustability and concomitant earth grading ability, it also introduces additional complexity into the control system, necessitating additional operator oversight. This is undesirable, requiring the operator to concentrate on monitoring two blade values on the display screen, and inputting two offset values into the controller, thereby necessitating additional input, time and distraction from other operational tasks, even in the majority of operating situations where only a single blade position is being varied.
Accordingly, there exists a need for a mode of operation of a guidance system that maintains the desired blade slope, regardless of elevation changes. There further exists a need for a mode of operation of a guidance system that provides the necessary blade adjustment information, but does so in a way that the amount of data presented to the operator is reduced, thereby simplifying the operator's task.